external isempty    : 'a list -> bool   = "isEmpty"
external llength    : 'a list -> int    = "len" 
external lsum       : 'a list -> int    = "sum"

let main () =
    let lst = [1;2;3;4;5;6;7;8;9;10] in
        let is = isempty lst in
        if is then
            Printf.printf "empty\n"
        else
            Printf.printf "not empty\n";
            let s = llength lst and v = lsum lst in
                Printf.printf "size : %d\n" s;
                Printf.printf "sum  : %d\n" v

let _ = main ()
